2 IntroductionAn op amp is an active circuit element designed to perform mathematical operation of addition, subtraction, multiplication, division, differentiation, and integration.A typical op amp: a) pin configuration, b) circuit symbol
3 Terminal Voltage and Currents Vd=V2-V1 (differencial input)Vo=AVd=A(V2-V1)A: gain (open-loop voltage gain)
4 i1i2Actual op amp: Ri(very large); Ro(very small); A(very large)Idealization: Ri=> ; Ro=>0 ; A=> As Vo is limited, we can get from Vo=A(V2-V1) that: V2=V1As Ri=> , we can get i1=0, i2=0
5 Ideal op ampIdeal op amp modeli1i2i1=0 , i2=0 ;V1=V2
12 P.P.5.10 As a voltage follower, va = v1 = 2Vwhere va is the voltage at the right end of the 20 k resistor.As an inverter, vb =Where vb is the voltage at the right end of the 50k resistor. As a summerv0 == [6 - 15] = 9V
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